cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 10 results.

A187106 Number of nonempty subsets of {1, 2, ..., n} having pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 495, 543, 615, 727, 1455, 1519, 3039, 3231, 3615, 3871, 7743, 7999, 11167, 11903, 14655, 15487, 30975, 31231, 62463, 69887, 76159, 80255, 89855, 91647, 183295, 192639, 208639, 214271, 428543
Offset: 1

Views

Author

Alois P. Heinz, Mar 06 2011

Keywords

Examples

			a(4) = 11 because there are 11 nonempty subsets of {1,2,3,4} having pairwise coprime elements: {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {3,4}, {1,2,3}, {1,3,4}.
		

Crossrefs

Cf. A036234. Row sums of triangle A186974. Partial sums of A186973. Rightmost elements in rows of triangle A187262.
Cf. A084422.

Programs

  • PARI
    f(n,k=1)=if(n==1, return(2)); if(gcd(k,n)==1, f(n-1,n*k)) + f(n-1,k)
    a(n)=f(n)-1 \\ Charles R Greathouse IV, Aug 24 2016

Formula

a(n) = Sum_{k=1..A036234(n)} A186974(n,k).
a(n) = Sum_{i=1..n} A186973(i).
a(n) = A187262(n,A036234(n)).
a(n) = A084422(n) - 1.

A187263 Number of nonempty subsets of {1, 2, ..., n} with <=2 pairwise coprime elements.

Original entry on oeis.org

1, 3, 6, 9, 14, 17, 24, 29, 36, 41, 52, 57, 70, 77, 86, 95, 112, 119, 138, 147, 160, 171, 194, 203, 224, 237, 256, 269, 298, 307, 338, 355, 376, 393, 418, 431, 468, 487, 512, 529, 570, 583, 626, 647, 672, 695, 742, 759, 802, 823
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Examples

			a(4) = 9 because there are 9 nonempty subsets of {1,2,3,4} with <=2 pairwise coprime elements: {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {3,4}.
		

Crossrefs

Column 2 of triangle A187262. First differences are A039649 for n>1.

Formula

a(n) = A187262(n,2).

A187264 Number of nonempty subsets of {1, 2, ..., n} with <=3 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 21, 25, 43, 54, 73, 83, 125, 136, 194, 215, 245, 278, 374, 396, 516, 552, 614, 662, 834, 871, 1018, 1087, 1215, 1285, 1555, 1592, 1900, 2023, 2181, 2298, 2506, 2581, 3013, 3160, 3378, 3497, 4027, 4105, 4689, 4875, 5103
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Examples

			a(4) = 11 because there are 11 nonempty subsets of {1,2,3,4} with <=3 pairwise coprime elements: {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {3,4}, {1,2,3}, {1,3,4}.
		

Crossrefs

Column 3 of triangle A187262. First differences are A186987.

Formula

a(n) = A187262(n,3).

A187265 Number of nonempty subsets of {1, 2, ..., n} with <= 4 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 53, 68, 97, 109, 193, 208, 345, 382, 437, 506, 785, 827, 1224, 1310, 1472, 1590, 2253, 2346, 2892, 3100, 3568, 3784, 5070, 5163, 6756, 7277, 7928, 8387, 9301, 9560, 12142, 12790, 13815, 14297, 17795, 18083, 22189
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Examples

			a(5) = 23 because there are 23 nonempty subsets of {1,2,3,4,5} with <=4 pairwise coprime elements: {1}, {2}, {3}, {4}, {5}, {1,2}, {1,3}, {1,4}, {1,5}, {2,3}, {2,5}, {3,4}, {3,5}, {4,5}, {1,2,3}, {1,2,5}, {1,3,4}, {1,3,5}, {1,4,5}, {2,3,5}, {3,4,5}, {1,2,3,5}, {1,3,4,5}.
		

Crossrefs

Column 4 of triangle A187262. First differences are A186988.

Formula

a(n) = A187262(n,4).

A187266 Number of nonempty subsets of {1, 2, ..., n} with <=5 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 225, 241, 450, 496, 565, 663, 1170, 1227, 2055, 2196, 2473, 2666, 4257, 4420, 5709, 6122, 7223, 7664, 11449, 11612, 16776, 18255, 19991, 21178, 23718, 24327, 33888, 35767, 38853, 40157, 54455
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 5 of triangle A187262. First differences are A186989.

Formula

a(n) = A187262(n,5).

A187267 Number of nonempty subsets of {1, 2, ..., n} with <=6 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 489, 537, 609, 719, 1383, 1446, 2674, 2851, 3204, 3443, 6110, 6329, 8484, 9083, 10930, 11587, 19252, 19471, 31084, 34131, 37428, 39637, 44583, 45640, 69968, 73870, 80421, 82985
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 6 of triangle A187262. First differences are A186990.

Formula

a(n) = A187262(n,6).

A187268 Number of nonempty subsets of {1, 2, ..., n} with <=7 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 495, 543, 615, 727, 1447, 1511, 2958, 3148, 3528, 3782, 7226, 7473, 10268, 10969, 13379, 14163, 25751, 25998, 45470, 50309, 55111, 58286, 65586, 67035, 112676, 118867, 129387, 133295
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 7 of triangle A187262. First differences are A186991.

Formula

a(n) = A187262(n,7).

A187269 Number of nonempty subsets of {1, 2, ..., n} with <=8 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 495, 543, 615, 727, 1455, 1519, 3031, 3223, 3607, 3863, 7646, 7901, 10987, 11719, 14393, 15219, 29383, 29638, 55637, 61912, 67681, 71466, 80284, 81965, 149001, 156985, 170628
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 8 of triangle A187262. First differences are A186992.

Formula

a(n) = A187262(n,8).

A187270 Number of nonempty subsets of {1, 2, ..., n} with <=9 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 495, 543, 615, 727, 1455, 1519, 3039, 3231, 3615, 3871, 7735, 7991, 11151, 11887, 14631, 15463, 30683, 30939, 60578, 67646, 73813, 77845, 87284, 89054, 171020, 179960, 195265
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 9 of triangle A187262. First differences are A186993.

Formula

a(n) = A187262(n,9).

A187271 Number of nonempty subsets of {1, 2, ..., n} with <=10 pairwise coprime elements.

Original entry on oeis.org

1, 3, 7, 11, 23, 27, 55, 71, 103, 115, 231, 247, 495, 543, 615, 727, 1455, 1519, 3039, 3231, 3615, 3871, 7743, 7999, 11167, 11903, 14655, 15487, 30951, 31207, 62147, 69503, 75765, 79855, 89440, 91230, 180285, 189556, 205432
Offset: 1

Views

Author

Alois P. Heinz, Mar 07 2011

Keywords

Crossrefs

Column 10 of triangle A187262.

Formula

a(n) = A187262(n,10).
Showing 1-10 of 10 results.